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Giving space it's place on the webTue, 03 Mar 2015 17:42:24 +0000en-UShourly1http://wordpress.org/?v=4.1Mid-2010: Atlantis’s First Last Flight and NASA’s Uncertain Futurehttp://www.nasaspaceflight.com/2010/12/mid-2010-atlantiss-flight-nasas-uncertain-future/
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]]>If the first third of 2010 represented an outstanding and unwavering commitment to safety and technical investigation/understanding, the middle portion of 2010 would bring with it not only a continued commitment to safety, but also a great deal of uncertainty over launch schedules, payload readiness, the status of orbiter Atlantis, and NASA’s overall future and direction.

A bitter sweet moment, the flight of STS-132 was (and technically still is) the 32nd and final flight of orbiter Atlantis, a vehicle which entered into service for the world community on Oct. 3, 1985 with the launch of STS-51J.

While the need to perform a full-up OMDP was set aside by a program decision reached after a year-long investigation into the flight number/year requirements for OMDP, the decision was made to incorporate some of the less intrusive and necessary flight safety OMDP inspections during the standard flow turnarounds for Atlantis – a process which began in 2008 when Atlantis was rolled back from Pad-A following the multi-month delay to the Hubble Servicing Mission.

While all of Atlantis’s Spar Structural fittings were not inspected prior to STS-132, a majority inspection allowed NASA to cleared Atlantis for flight based on the extremely positive results from the spar fittings inspections performed both in her flow toward STS-129 and toward STS-132.

With these inspections in place, the Atlantis team completed OPF processing in early-April.

Walked from the OPF by her processing team, technicians stopped Atlantis half-way down the transfer lane for a special photo op for all interested KSC employees and media officials present. The special photographic opportunity allowed KSC workers time to reflect on the nature of Atlantis’s numerous missions – of which a vast majority were dedicated to the pursuit of international interests – and the overwhelming history of the orbiter herself.

After a three hour stop, Atlantis was moved the rest of the way into the VAB and mated to her ET/SRB stack.

The amazingly clean nature of Atlantis’s STS-132 launch campaign led Russian Space Agency official Alexey Krasnov to state in the STS-132 Post-Launch News Conference that this entire launch flow was Atlantis’s way of screaming “use me again!”

But it wasn’t just the amazing and outstanding success story on orbit that highlighted the Atlantis mission, it was also the extraordinary work on the ground by the imagery analysis teams that shone through during the May flight.

Initial thoughts of implementing a modified OBSS late-inspection to counter the images obtained or not obtained during the FD-2 inspections when the OBSS cable was snagged around the instrument platform were discarded thanks to the work performed on the ground.

But even that role was in question in the first few weeks following the completion of STS-132 as internal NASA documents routinely placed Atlantis’s status as “Under Review” instead of in processing. At work here was more than just a simple uncertainty of Atlantis’s future, but an overall uncertainty of NASA’s future.

STS-134 was subsequently advanced by one day to February 26 before moving to April 1 as a result of continuing safety-conscious delays to the STS-133/Discovery mission.

With these delays, the Space Shuttle Program officially moved into 2011, a move that caused initial concerns over whether the program would have the money to execute a full-up flight in 2011 with the proposed FY2011 budget from President Obama.

However, NASA, ever diligent, created a plan to save money and create a monetary cushion to allow STS-134 to fly in the 2011 timeframe.

The Fight for NASA’s Future:

As the year began, NASA and space enthusiasts alike waited word from President Obama as to his vision for NASA’s future – a vision many had been waiting for for nearly a full calendar year.

On February 1, President Obama unveiled his FY2011 budget proposal… a proposal that included his vision for NASA – a vision that quickly garnered significant scrutiny and reactions from across the political spectrum.

However, while these issues of manned U.S. space exploration were certainly the most controversial talking points of the President’s proposal, it is just as important to note the utmost and high support the President showed for the International Space Station, interplanetary robotic exploration missions (specifically designed as precursor missions for manned planetary exploration), and both land-based and space-based medical research – support which, to some, was equally surprising but highly welcomed.

To this end, both the House and Senate passed different bills initially. Since, under U.S. law, both bills would have required reconciliation into one bill – approved then by the House and Senate – before being sent to the President’s desk for approval or veto, a compromise in the bicameral legislature was proposed and submitted for review by the House Committee on Science and Technology.

The 168 page compromise bill, released by the House Committee on Science and Technology which is led by Rep. Bart Gordon from the state of Tennessee, stated: “In the 50 years since the establishment of NASA, the arena of space has evolved substantially.

As the uses and users of space continue to expand, the issues and operations in the regions closest to Earth have become increasingly complex, with a growing number of overlaps between civil, commercial, and national security activities. These developments present opportunities and challenges to the space activities of NASA and the United States.”

But with all things political, the fight for NASA’s future would not end with the passage of and signing into law of the 2011 NASA Authorization Act. Since Congress could not pass the necessary funding bill for FY 2011 (Fiscal Year 2011) before the start of the FY on October 1 (a date which seems to surprise Congress each year), a Continuing Resolution – funding NASA at the previous FY’s level – was passed by the House and Senate.

This Continuing Resolution took NASA through mid-December, but greatly inhibited the agency’s ability to move forward on the initial designs of a new Heavy Lift Vehicle as well as officially adding the STS-135 mission to the launch manifest.

Since, during the lame-duck Congressional session in December, the Senate and House also failed to reach a compromise on the FY2011 budget, another Continuing Resolution was passed to fund the U.S. government and its agencies into March 2011 – thus leaving the new Congress, which convenes next week, to tackle the FY2011 budget.

Thus, as it currently stands for the Space Shuttle Program, STS-134/Endeavour will be the final Program flight. While many are confident that the Continuing Resolution to March 2011 will provide NASA the money needed to transition STS-335 into the full-up STS-135 mission, NASA has not made any leanings in that direction just yet.

]]>http://www.nasaspaceflight.com/2010/12/mid-2010-atlantiss-flight-nasas-uncertain-future/feed/0STS-132’s OBSS cable snag sets up potential mitigation planhttp://www.nasaspaceflight.com/2010/07/sts-132s-obss-cable-snag-potential-mitigation-plan/
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]]>Following the snagged cable incident on Atlantis’ Orbiter Boom Sensor System (OBSS) Pan Tilt Unit (PTU) during STS-132, the Program Requirements Control Board (PRCB) have outlined their investigation findings, and a potential mitigation plan. Later this month, engineers will test the addition of a permanent cable tie, in order to avoid future snags.

OBSS PTU Snag:

The OBSS and its sensor package are one of the unsung heroes of the Return To Flight (RTF) era, allowing for post-launch and pre-entry inspections of critical area of the orbiter’s Thermal Protection System (TPS).

Teamed with an arsenal of imagery footage and expert engineers with the Damage Assessment Team (DAT) in Houston, all post-Columbia missions have successfully returned with added – and justified – confidence in the health of the heatshield.

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The evaluations into the TPS begins as soon as the shuttle launches, with ground-based cameras and radar tracking debris hazards, working in tandem with orbiter based assets, such as the ET cameras and crew photography footage of the tank – the main source of debris threats.

Flight Day 2 is highlighted by the first use of the OBSS during the mission, focusing on three primary areas; the nose cap and the port and starboard Wing Leading Edges (WLE) – ensuring the Reinforced Carbon Carbon (RCC) panels avoided damage during ascent.

STS-132’s FD2 inspections began without issue, with the OBSS unberthed, followed by the activation and calibration of the Laser Dynamic Range Imager (LDRI) on the boom’s sensor suite. A quick check for ice on the starboard T-0 umbilical was followed by a robotic translation to the start point for the starboard wing survey, which revealed an issue with the PTU.

“Background of Issue: During the beginning of STS-132 FD2 Inspection procedures, PTU readings and behavior were erratic and eventually lead to determination that it was not able to move the entire tilt range,” noted the PRCB presentation, available on L2.

Ground controllers asked the crew to reset the PTU in an effort to correct the issue, prior to the crew visually noticing a cable – known as the W601 cable – was snagged on the unit’s protruding reed sensor.

“All attempts to resolve were unsuccessful: Crew manipulation, ground control manipulation, change in PTU speed. PTU was unable to point to the tilt values required to support FD2 Inspection. A cable snag was confirmed by the crew viewing PTU motion from the Flight Deck windows.”

Meanwhile, the Mission Management Team (MMT) asked KSC engineers to look into how the snag could have occurred, checking closeout photos of the OBSS PTU ahead of Payload Bay Door (PLBD) closure for flight, along with flight history and checks into replaced elements of the hardware.

“Full pan and tilt range was confirmed post re-assembly during the STS-132 Pre-Installation Acceptance (PIA) testing with no issues of a cable snag. Installation procedures and close out photos were reviewed – no indication of incorrect installation. S/N 1002 Cable has flown on STS-130, STS-128, STS-125, STS-123/124, STS-115, STS-114.”

“In-Flight Resolution: During EVA2, the cable was physically removed from the snag point and an additional cable tie was installed to preclude the snag from reoccurring. Full PTU pan and tilt motion was restored and Late Inspection was performed nominally.

“Photos of flight hardware post STS-132. Red circles are area of snag occurred.”

Post Flight Troubleshooting:

Once Atlantis was back inside her Orbiter Processing Facility (OPF-1), engineers began a hands-on inspection of the PTU by removing the unit from the OBSS, part of the nominal procedures for preparing the PTU for its next flight, although this time including the enforced changeout of the troublesome cable.

Implementing part one of the plan, engineers cut the cable tie installed during EVA-2, and attempted to perform the movement of the PTU with the old W601 cable that snagged during FD2 inspections. Just like it did on orbit, the cable snagged several times during ground testing.

“Cable laid flush against the PTU tilt ring at +102, -252 (pan, tilt). Moved PTU pan to +85 and the cable remained against the tilt ring. When the PTU was tilted up, it was observed that the cable snagged against the fixed electronic stop (Reed Sensor).

“It was concluded that the cable had to have been laying flat against the tilt ring at +102, -252, when the crew began panning and tilting in slow rate in order for the cable to snag. Able to recreate this scenario multiple times using W601 cable SN 1002.”

Engineers then replaced the old W601 cable with a new spare, re-performed the movement of the PTU, and successfully avoided the cable snagging during the tests.

“With successful recreation of the issue, W601 cable S/N 1002 was changed out with S/N 1005. Motion of PTU and cable characteristic was verified – values per PIA procedures, which include full range of motion, and on-orbit operational values.”

Forward Plan:

As to what caused the old cable to snag on the reed sensor during STS-132, and how can such a situation be avoided in the future, engineers checked to see if the W601 cable was somehow being pressed against the PTU after the Payload Bay Doors have been closed – in other words, if hardware was breaching into the space (envelope) of where the cable was positioned.

“Envelope Measurement History: Each of the three fully assembled SP1 units were measured for dynamic envelope to confirm clearance to the radiators and to any stowed payload,” added the presentation.

“Current Active Sensor Pack 1s: S/N 1003 with W601 cable S/N 1005. S/N 1007 with W601 cable S/N 1003. During this activity, it was noticed that each W601 cable has its own characteristics with respect to routing, translation and memory.”

With those findings – showing it may be an uncontrollable issue if left as-is – the Orbiter Project Office (OPO) will test the potential of added an additional cable tie, in order to guarantee the W601 cable avoids being pressed into a position that threatens it subsequently being snagged on the reed sensor.

“OPO has requested to assess the envelope measurement with the additional cable tie. Pending confirmation of positive envelope impacts, cable tie will remain in place for flight,” confirmed the conclusions to the presentation.

Testing on the viability of adding a new cable tie will take place during the week of July 26.

]]>As the era of large Solid Rocket Boosters (SRBs) for NASA launch vehicles appears to be drawing to a close, the performance of STS-132’s booster set was recorded as excellent at the In Flight Anomaly Review (IFA). In total, zero IFAs were recorded on the Reusable Solid Rocket Motors (RSRMs) – with only four minor squawks, adding to the nine minor squawks and one IFAs on the SRBs.

Only one IFA was recorded via the SRB IFA review – all 16 STS-132 IFA presentations available on L2 – relating to missing insulation from Forward Booster Separation Motor (BSM) Closeout – which is classed as an unacceptable debris hazard.

“RTV-133 Missing and Partially Debonded from Forward Booster Separation Motor (BSM) Closeout: Located on perimeter of upper right BSM – Size ~ 5 in long x ~ 1/4 in fillet bead. Unexpected debris source (not allowable),” noted the presentation, which added the loss of the insulation during ascent held no issue for the booster’s performance.

“Functions as environmental seal only. Not intended for thermal protection evaluation found heat effects and sooting not as severe as full flight but greater than adjacent area with intact RTV-133.”

Although its location is an unacceptable debris hazard, it is not clear if the material had enough mass to be a threat to the orbiter’s Thermal Protection System (TPS). However, no impact with the orbiter was noted, although an investigation is still ongoing as to the root cause of the liberation.

“Late ascent time of occurrence not ruled out – and also observed RTV-133 debonds associated with BSM closeout,” the presentation added. “IFA declared and Anomaly Resolution Team (ART-279) formed to investigate anomaly. Fault tree baselined and investigation ongoing.”

Squawks are minor issues which fail to be upgraded into a full IFA, with STS-132’s boosters listing nine – a low number – such items of interest in the review.

Squawk 132-002 provided a good example as to just how extensive the boosters are evaluated, even – in this case – before they launch, whist also showing how minor a squawk can be, with the blue material found to be nothing more than printer ink.

The performance of STS-132’s RSRM set 111 was classed as within specifications and overall ‘excellent’, although their inspection process takes slightly longer, and involves evaluations once the motors have returned to ATK’s base in Utah. So far, no IFAs have been declared, as engineers push forward towards their +180 days report.

“All RSRM countdown parameters were within LCC (Launch Commit Criteria/OMRS limits and within family,” opened the ATK presentation to the STS-132 IFA review (L2). “Overall performance of both RSRM motors and all ATK BSMs excellent and well within requirements.

“RSRM postflight hardware evaluation is ongoing: KSC – in work. Aft BSM and RH field joint assessments still to be performed. Utah – in work. Nozzle joint disassembly complete. No IFAs declared at this time.”

Only four squawks – two related to the same issue – were written, all of which have been reviewed and classed as no impact to the performance of the hardware.

“Overall performance of both STS-132 (RSRM-111) motors and ATK BSMs were excellent. Postflight evaluation is still in work. Four squawks have been written at this time. No IFAs declared at this time but additional postflight disassembly and evaluations are still in work,” added the introduction.

Two of the squawks were charged against the Left Hand (LH) Booster Separation Motor (BSM), relating to insulator-to-closure edge unbonds on serial numbers 232 and 233. Due to the lack of debris or motor performance concerns, this issue was not elevated to become an IFA.

The issue is also classed as likely to have occurred during splashdown in the Atlantic ocean, as opposed to during any phase of the powered ascent of first stage flight.

“Creation and growth of unbonds during post-operation heat soak and splashdown is expected,” noted the presentation. “No mechanism exists for creation of unbonds prior to post-operation heat soak.”

The third issue related to the Right Hand (RH) Nozzle Leak Check Barrier O-ring Groove on the Aft Edge Corner – which suffered from phenolic damage. No compromise to joint performance was noted.

“A small area of damage to the RH nozzle-to-case leak check barrier O-ring groove aft corner was observed at 308 degrees,” noted the presentation, which added the cause is still being investigated.

“Cause determination is still in work but loss is not expected to compromise thermal barrier capability of the leak check barrier O-ring or decrease the expected joint performance in the event of pressure reaching the leak check barrier O-ring.”

The final note on the IFA presentation referenced a blister on the insulation associated with the Right Hand Igniter Chamber. The blister was noted as a manufacturing defect with no impact to igniter performance.

“Unusually shaped feature (roughly 0.5” by 2”) was noted on the ID of the RH igniter chamber. Squawk was written to permit evaluation,” the presentation continued.

“A portion was excised which verified the observation was a blister and had no signs of thermal effects or sooting. Engineering allows blisters of this size in this region of the igniter.”

Proof the shuttle’s recent performance has been recognized by the engineering and political communities can also be seen via such extension debates, which now focus mainly on cost, as opposed to safety concerns.

]]>An In Flight Anomaly (IFA) Review into STS-132’s ascent has noted an observation of over 200 streaks from Atlantis’ Space Shuttle Main Engine (SSME) plumes during ascent. While the number of streaks is twice the amount of the previous “record” no loss of performance or safety margins were breached. Meanwhile, Discovery has received all of her SSMEs back, following the removal of the engines last week.

“Engine relief valve checks were completed Tuesday; post-ops are scheduled to complete Wednesday,” added the NTD. “LH/RH (Left Hand/Right Hand) translators were opened Tuesday in support of SSME installation which began on Wednesday.”

UPDATE: However, on Thursday – according to the NTD – the last of the three SSMEs was already being installed. Due to the new positions, only ME-1 would need to be removed, if the same issue repeats itself during testing. Previously, all three engines had to be uninstalled to allow for ME-1’s removal from its center position, due to interferences.

Meanwhile, in the Vehicle Assembly Building (VAB) High Bay 3 (HB-3), final torque and leak checks between the mated External Tank (ET-137) and the twin Solid Rocket Boosters (SRBs) are in the process of being completed this week.

Streaks in the engine plumes are not uncommon. However, the number of observations seen during Atlantis’ first stage ascent earned a mention in three presentations at the STS-132 IFA review – primarily on the Pratt and Whitney SSME presentation to PRCB-level managers.

The performance of Atlantis’ engines – E2052, E2051 and E2047 – during what is currently her final mission was classed as nominal at the SSME IFA Review, with only a frayed Flow Recirculation Inhibitor (FRI) note added to the aforementioned observation of streaks in the SSME plumes.

FRI is filled ceramic fiber tube installed in the space between nozzle tubes and MCC wall at the G15 joint. The fact such a small observation was even listed in the IFA review is a testament to the inspection process, and historical performance of the engines.

“FRI protects G15 Bellows Seal from overheating by reducing recirculation of hot gas into G15 cavity. FRI degradation is a normal wear issue with hot fire exposure. Function is maintained with fraying,” added the presentation, before noting hot fire experience for added confidence the issue held no safety concerns.

]]>http://www.nasaspaceflight.com/2010/06/streaks-atlantis-ssmes-noted-discovery-gains-two-engines/feed/0Excellent External Tank TPS performance reduces pull test requirementshttp://www.nasaspaceflight.com/2010/06/external-tank-performance-reduces-pull-test-requirements/
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]]>A multi-stage approach to the mitigation of foam liberations from the intertank region of the External Tanks (ETs) continues to pay dividends, as STS-132’s In Flight Anomaly (IFA) review pointed to yet another clean tank – with only one area of notable foam loss from Atlantis’ tank. The results have removed the requirement for additional plug/pull tests on STS-133’s ET.

STS-132’s ET-136 Review:

The performance of the foam Thermal Protection System (TPS) on the ETs – specifically the liberations that occur during the ride uphill – has been one of the key drivers for the successful and safe completion of the Shuttle manifest.

Noted as a science by former Space Shuttle Program (SSP) Wayne Hale, the protection against serious foam liberations – from critical areas, and at critical times of ascent – is the ultimate driver for protecting the orbiter’s heatshield. The result has been a run of orbiters returning to Earth with nothing more than cosmetic damage.

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Return To Flight modifications to the tank continued throughout the second half of the last decade, with further lessons learned on areas such as the Ice Frost Ramps (IFRs) – which have seen hardly any foam shedding since redesigns were implemented.

However, before a tank leaves the pad with the rest of the stack, the three hour process of loading the ET with LH2 and LOX requires the hardware to perform as advertised, notably of late with the Ground Umbilical Carrier Plate (GUCP) – the cause of scrubs during both STS-119 and STS-127.

Since a redesign to a two-part seal – and the correction of misalignments on the External Tank Carrier Assembly (ETCA) mounts, or feet – no leaks have been detected during topping operations, as was the case with STS-132.

“Pre-launch Performance Assessment: Electrical and Propulsion systems performed nominally. No leakage detected at the GUCP during the transition to topping. Total of ten (10.3) pre-press cycles as predicted,” noted the STS-132 External Tank IFA Review presentation – all 16 IFA presentations available on L2.

Several observations were logged after tanking by the Final Inspection Team (FIT), who photograph the tank for issues such as ice build up and any cracks caused by the cryo conditions associated with tank loading. However, all were cleared during the business end of the countdown by the Mission Management Team (MMT).

Only three areas of foam loss – four events in total – were noted on the IFA presentation, all deemed as minor. None of the liberations are believed to have impacted the orbiter – although none would have threatened any damage of note on Atlantis’ TPS due to their small mass.

“Post flight performance assessment identified the following ET TPS debris events of note in critical debris zone for further scrutiny,” the presentation continued.

Only the intertank loss occurred near to the time foam liberations may have enough energy – via the remaining air resistance as the stack leaves the atmosphere – to be a threat to the orbiter, although it would have had to been of a higher mass in such an event.

“Intertank imagery reveals only one loss similar to those as observed on ET-131 (low bond adhesion induced losses with stringer top primer visible), and no losses observed from bond adhesion test repair sites,” the presentation noted.

While bond tests – sometimes known as plug/pull tests – will continue to be carried out in the Vehicle Assembly Building (VAB), engineers are not required to carry out additional tests on additional areas, as previously called for.

“Intertank acreage foam loss at Xt 1102. Failure mode not documented – IFA recommended (IFA-STS-132-T-002). This loss is consistent with our understanding of this failure mode and within expectations since this failure mode was identified on ET-131.

“No additional bond adhesion tests are planned for ET-137 based on process similarity and performance of ET-136.”

All other areas of the tank, which have suffered from foam liberations during flights in recent years, were classed as clean, confirming the excellent performance of the tank. These results will next become part of the baseline for the STS-133 Flight Readiness Review (FRR).

]]>http://www.nasaspaceflight.com/2010/06/external-tank-performance-reduces-pull-test-requirements/feed/0Atlantis ready for STS-335 flow following impressive mission performancehttp://www.nasaspaceflight.com/2010/05/atlantis-sts-335-flow-following-impressive-performance/
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]]>After what is becoming more likely to have been her last flight, Atlantis is continuing post roll in operations, as she prepares to head into STS-335 processing in support of STS-134. If STS-132 proves to be Atlantis’ swansong, the post-flight reports from the Mission Management Team (MMT) point to a superb performance during entry and landing, arriving home in near-pristine condition.

STS-132 Re-entry/Landing:

Atlantis arrived back home in Florida with only nine reported issues in the Mission Evaluation Room (MER) – the last relating to the Flash Evaporation System (FES) during deorbit preparations. The FES provides cooling to orbiter systems when the Payload Bay Doors (PLBDs) – which include the radiators used on orbit – are closed.

“The FES in topping mode using the primary B controller shut down near the end of the radiator coldsoak for deorbit prep. The shutdown occurred about 46 minutes into the radiator coldsoak. The crew then restarted the FES topper using the primary B controller,” noted the post flight report to the MMT (L2). This resulted in a shutdown with the FES Freon outlet temperature failing to reach the control band.”

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As part of the malfunctions handbook, the crew followed a procedure that has been used a couple of times on recent flights, known as a core flush – which is one solution for ice buildup in the FES. Contingency exists in the system if required.

“Subsequently, the crew restarted the FES using the primary A controller resulting in a successful seven minute operation, via a contingency procedure using a modified radiator bypass/FES checkout with core flush (on secondary controller) followed the primary A activation.

“In this contingency procedure, the FES is operated in secondary high load mode, followed by a core flush, then concluded with secondary topping operation. Ice and excess carryover were observed in the FES topping ducts during the core flush. The core flush stage of the procedure was performed twice because the initial core flush produced duct temperatures that indicated ice had not been completely flushed from the core.

“The second core flush produced duct temperature signatures that indicated a complete flush of the core. After completion of the contingency procedure, the FES configuration was switched to primary A controller in full up mode which prepares the orbiter for deorbit. Entry operations on the FES Pri A controller were nominal.”

With the FES issue resolved, both PLBDs were closed nominally by 146/03:49:08GMT [11/09:28:59 Mission Elapsed Time (MET)] in preparation for landing. A delayed closed indication on the starboard door has previously occurred several times in the past on multiple vehicles and is a known condition, thus was not a concern for entry.

The deorbit maneuver for the first landing opportunity at KSC, a dual-engine straight-feed firing, was started on orbit 186 at 146/11:41:59.2 GMT (11/17:21:51.2 MET) with shutdown at 146/11:45:05 GMT (11:17:24:57 MET). The burn was 185.6 sec in duration with a delta V of 333.6 ft/sec.

Atlantis’ Fuel Cells and Auxiliary Power Units (APUs) all performed as advertised, after holding a good level of reserve in case of weather related wave offs.

“All APU parameters were nominal on the final day on-orbit (FD13), during entry, and postlanding at KSC. APU 2 was the TIG-5 single APU start, APU 1 and 3 were started at EI-13,” added the MMT overview.

“The fuel cells generated 13.8 kW and 449 amps, average, and 3896 kWh of total electrical energy during the 282.48 hour mission. The fuel cells consumed 337 lb of hydrogen and 2673 lb of oxygen from the PRSD (Power Reactant Storage and Distributation) subsystem. The PRSD system also provided 234 lb of oxygen to the crew. The fuel cells produced 3009 lb of water. Approximately 44 lb of O2 was used for tank-to-tank transfer to ISS.

“The PRSD subsystem could have supported a 75 hour mission extension at the average mission power level of 13.8 kW based on the usable quantities remaining at landing. At an extension day average power level of 12.51 kW, it could have supported an 83 hour mission extension.”

Pages of reports on the numerous orbiter systems – used during the transition from a spacecraft to an aircraft – all listed nominal performance, ahead of the wheels touching down on Runway 33 of the Shuttle Landing Facility (SLF).

“Great effort on the flight, both the prep to get the vehicle ready and during the flight,” noted Shuttle manager John Casper on the latest Shuttle Standup/Integration report (L2).

“(Thanks to) the Ground Operations team for all their outstanding work to get Atlantis ready to fly, and now putting back in the OPF (Orbiter Processing Facility).”

Post STS-132/STS-335 Processing:

It takes around a week of operations to safe an orbiter in preparation for their next flow, with Atlantis set to be processed as the STS-335 vehicle in Launch On Need (LON) support of Endeavour’s STS-134 flight – although the final manifest running order is yet to be finalized – not least if STS-135 will be added, and which orbiter will fly the mission, with a June 2011 launch date preferred.

Following landing on the SLF, the Convoy engineers completed Atlantis’ total downgrade at 0953 EDT, ahead of tow operations to OPF-1, which began at 1244 EDT. This marked the start of OPF Roll In Operations.

“S0069 Integrated OPF Roll In operations: The vehicle was spotted in the OPF at 1604 EDT. Fuel cells were powered down at 2224 EDT. Jack & level was completed at 0054 EDT. T-0 and Horizontal drain/control venting is in work,” noted the opening STS-335 notes (L2) from the NASA Test Director (NTD).

“Cryo drain and tank inerting is complete. Orbiter power system validation and PLBD strongback installation (Friday). PLBD functional is scheduled for Tuesday.”

“New IPR 0004: O2 Tank 4 Midbody connection near Door 45 Leak exceeded allowable level. Problem was detected during preps for Cryo drain. It was determined to be a fuzz leak at the QD. It was determined to not be hazardous since the QD only passes GHe. Engineering suspects a possible nose seal issue and will inspect the QD at a later time. No constraint to continue with Cryo drain/inerting.”

Engineers will work on Atlantis on Saturday, prior to a two day break over Memorial Weekend, with only the requirement to establish Orbiter Aft access on the books.

]]>Shuttle Atlantis has managed to dodge unacceptable weather at her home port of the Kennedy Space Center (KSC) on Wednesday, taking the first of the two Florida landing opportunities, ending in a graceful landing. For what may of been her final day in space, Atlantis continued to be in great shape, with only the observation of two debris events during Flight Day 12 checks requiring the attention of the Mission Management Team (MMT).

STS-132 Status:

The opening landing opportunity called for the deorbit burn to occur at 7:41am Eastern, resulting in a perfect landing on runway 33 at the Shuttle Landing Facility (SLF) at 8:48am.

The second – and final – opportunity would have been available one orbit later, with the deorbit burn at 9:17am for a landing at 10:22am. However, this was not required, along with EOM+1 (End Of Mission plus one day), and “pick em” day on Friday, when the Edwards Air Force Base (Dryden Flight Research Facility) would have been brought into the mix.

See Also

Some level of troubleshooting was worked on the Flash Evaporator System (FES), which will control Atlantis’ temperatures after the Payload Bay Doors (PLBDs) are closed, removing the radiator’s ability to cool electronics and other systems on the orbiter. This issue was soon resolved, allowing for the closure of the PLBDs.

The results of the Late Inspections showed an extremely clean Atlantis, and a good argument for her being classed as the cleanest orbiter in at least recent history, with only 252 ROIs (Regions Of Interest) – areas that need any checks, such as scuffs and stains – a number which is the lowest since the use of the OBSS, and nearly half the number observed on STS-131.

“LESS/RCC team cleared all late inspection regions of interest. Level 1 review by PRT completed at 5:00 pm (5-24). Level 2 completed at 1:00 am. Final PRT Review completed at 6:52 am (5-25),” noted the DAT findings presentation (L2). “No ROI exhibited any damage characteristics. From all of the early/late inspection LDRI imagery LESS PRT is GO for entry.”

The robotic duo responsible for the survey – the OBSS on the end of the SRMS (Shuttle Remote Manipulator System) – were successfully reberthed in the Payload Bay for the return home, marking the end of their operations for the mission.

“On FD 11 (Flight Day 11), the OBSS and RMS were successfully berthed, latched, and stowed and are in a good configuration for payload bay door closure, entry, and landing,” noted the Mission Evaluation Room (MER) report on L2.

“OBSS BERTH and MRL LATCH. Did not receive the Aft MRL Latch 2 indication (known condition), no further action required. All other indications nominal. Good single motor drive time RMS BERTH and MRL LATCH – All indications nominal, good dual motor drive time.

“FD12 Performance: All APU parameters are nominal. All APU heaters are functioning nominally on the ‘B’ string. The GG heater lower set point shift – unique to OV-104 (Atlantis) position #1 since STS-81 – is evident after about six B heater cycles, exactly the same as on the previous OV-104 mission, STS-129 (31). This heater signature was expected and will be noted in the MER trending database.”

“Object estimated size: 0.44” – Does not emerge into provided FOV from bottom, so there is not evidence as with the other FOD that it emerged from the PLB. However, it is first seen against the wing background (i.e. it’s much closer than the wingtip on first appearance. Estimate above assumes that it did come from PLB. 32 inch range (max) estimated to object.”

Both objects appear to be similar, but have not been identified. However, no concerns were raised by the MMT, and such debris events can occur during the vibrations of FCS checkouts.

“The Flight Controls System Checkout was performed. The procedure was completed with nominal results. The team is not working any issues,” confirmed the MER via their latest shift report, reviewing Flight Day 12’s activities. “Monitored FCS Checkout and RCS Hotfire. Two Foreign Object Debris (FOD) items were observed floating away from the Orbiter during FCS checkout.

“Imagery personnel recorded video of the FODs, and did not feel that they would pose a threat to the Orbiter TPS, since they were small (<1″), appeared to originate from the upper surface of the Orbiter and were floating away from the vehicle.”

“38 of 38 primary thrusters have been fired. Thirteen (13) new Primary thrusters were fired since previous report,” noted the MER. “All thermal systems are performing nominally (except L3D thruster heater) and temperatures are within acceptable limits. The L3D temperatures are currently near 56F.”

]]>As Atlantis’ crew complete final checkouts for entry and arrival back home at the Kennedy Space Center, the Damage Assessment Team (DAT) have successfully concluded their thorough review of Atlantis’ fragile Thermal Protection System (TPS) – clearing the vehicle’s heat shield for entry. Two landing attempts available for Atlantis on Wednesday morning – the first at 0844 EDT and the second at 1023 EDT.TPS DAT Overview:

The Mission Management Team (MMT), with information from the DAT and OPO (Orbiter Project Office), officially cleared Atlantis’ TPS for reentry – following a long and arduous process of gathering all the necessary inspection data via Atlantis ‘Orbiter Boom Sensor System (OBSS), R-bar Pitch Maneuver (RPM) photography from ISS, and EVA (Extravehicular Activity) photography opportunities.

“Lighting and viewing angles sufficient for assessment of forward edge,” notes the presentation. The paint stripe used to verify ET door closure was – as expected – not visible from RPM photography, confirming Atlantis’ computer data that the ET doors are closed and properly sealed for entry.

“Closure indicators not visible in imagery and no evidence of off nominal steps or thermal barrier protrusions [are present]. ET Doors are closed.”

Interestingly enough, all TPS damage locations for STS-132 are located on the port (or left-side) of Atlantis, with the two tile damage areas located on the port Nose Landing Gear Door (NLGD) and just outboard of the left-aft corner of the Port ET Umbilical door (and just inboard of the forward, starboard corner of the inboard Elevon), respectively.

For the damage location on the NLGD, the DAT summary notes that the tile in question is 1.7-inches thick with a missing “putty repair” of 1.2-inches in length, 0.6-inches in width, and 0.1-inches in depth.

Resulting damage dimensions are estimated at 1.89-inches in length and 0.49-inches in width with “photogrammetry determined depth [at] 0.2-inches.”

This damage area is of no concern for entry and was cleared using P-DAT.

These tools yielded “high” confidence in the damage analysis to the tile in question. Overall, this tile is 1.15-inches thick with photogrammetry damage estimated at 2.25-inches long, 0.97-inches wide, and 0.15-inches deep (+/- 0.05-inches).

However, clearance of this tile damage could not be had without consideration of the upstream AMES Gap filler which could affect the airflow and local heating environment around the damaged tile.

For this protruding AMES Gap filler, “Thermal bounded by previous analysis that showed transition at M=18 (keq=.25) acceptable in this area,” notes the DAT summary.

Furthermore, a “Partial transition load comparison based on aeroheating heat loads” was performed as well.

A reference point to a previous analysis “which used partial transition load cases” developed for nonstandard processes was also used to clear the gap filler itself.

In all, the AMES Gap filler is protruding 0.24-inches (+/- 0.15-inches) in a non-reworked area of Atlantis Gap fillers located inboard of the Port Main Landing Gear Door (MLGD).

Since most of the Gap filler remains in the gap, liberation during reentry is not expected as ascent loads on the Gap filler are “several times higher than entry loads.”

Furthermore, considerable flight history with protruding Gap fillers is on file and was used to clear the Gap filler.

In fact, a chart of the historical Gap filler protrusions since Return to Flight in July 2005 showed three Gap filler protrusions with comparable or greater protrusion Height Maximums (Hmax); STS-124: Hmax= 0.23-inches; STS-120: Hmax= 0.29-inches; and STS-121: Hmax= 1.04-inches.

However, given the range of height uncertainty (+/-0.15-inches) with this particular Gap filler, it is possible that the Gap filler could trip the Boundary Layer at Mach 18 during reentry, creating a potential off-nominal heating effect on downstream areas of the vehicle, most notably the damage site of damaged TPS tile #2.

Therefore, while the Gap filler itself was cleared for entry, its affect on the lower surface aft TPS tile damage location had to be evaluated before that TPS tile damage site could be cleared for entry.

In all, it was determined that if the boundary layer is tripped at March 18 by the protruding Gap filler, the structural area directly below the damaged tile would see temperatures below 350˚F with just a small potential RTV overtemp: 2.79in2 normal flow.

Maximum structural temperature expected in the region is 246˚F, only 6˚F above the standard 240˚F baseline temperature. Therefore, positive structural margin is maintained and no concern exists for the damaged TPS tile due to upstream affects from the protruding Gap filler.

Finally, the last area of Atlantis’ TPS to come under scrutiny from the DAT was a partially frayed outer layer on one FI blanket on the Port OMS pod.

The blanket in question is 1.6-inches thick and all blanket insulation remains intact – thus, thermal performance is maintained. Liberation is not expected due to previous experience with “frayed outer covers and loose patch repairs.”

Currently, it is believed that the blanket was damaged on the ground during final vehicle configuration for flight as the blanket is located next to a door that is removed each flow for access inside Atlantis.

In all, the extremely clean nature of Atlantis’ TPS tiles has led to the unanimous decision by the OPO and DAT to recommend the TPS tiles and blankets cleared for reentry.

Final clearance of the entire TPS (including the all-important RCC panels and nose cap) was approved earlier this morning by the MMT following a complete review of the RCC Wing Leading Edge panels and nose cap imagery from the OBSS late-inspections yesterday.

Thus, weather permitting, Atlantis has been cleared for her final landing at the Shuttle Landing Facility (SLF) Wednesday morning.

If all goes according to plan, Commander Ken Ham will ease Atlantis onto runway 33 (the southeast to northwest approach to the SLF) at the Kennedy Space Center at 0844 EDT, capping a near 12-day flight for Atlantis and the STS-132/ULF-4 mission.

]]>http://www.nasaspaceflight.com/2010/05/sts-132-dat-clear-atlantis-tps-for-landing/feed/0Atlantis Undocks from ISS; Potential Thruster Heater Failure Workaroundhttp://www.nasaspaceflight.com/2010/05/atlantis-undocks-from-iss-potential-thruster-heater-failure-workaround/
http://www.nasaspaceflight.com/2010/05/atlantis-undocks-from-iss-potential-thruster-heater-failure-workaround/#commentsSun, 23 May 2010 15:29:56 +0000http://www.nasaspaceflight.com/?p=14779
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]]>Following a spectacularly successful docked mission to the ISS, Atlantis has undocked from the orbiting international science laboratory for the final time in her career. Meanwhile, should mission managers deem necessary, a week’s worth of investigation into the L3D thruster heater failure has produced a potential workaround for the failed “off” heater during post-undock operations.

L3D Thruster Heater Failure Overview:

Following a week of docked operations, orbiter Atlantis has completed her 11th and final docked mission to the International Space Station, capping an amazing career of 18 total dockings to MIR and the ISS (7 to MIR and 11 to ISS).

Currently, Atlantis will spend two more days in Low Earth Orbit, with the all-important late-inspection of the ship’s RCC (Reinforced Carbon-Carbon) WLE (Wing Leading Edge) panels and Nose Cap occurring on FD-11 (Monday). Then, on FD-12, Atlantis’ crew will begin preparing their ship for reentry by testing the various systems they will use for Entry, Descent, and Landing and reconfiguring Atlantis’ middeck for entry.

See Also

Finally, on FD-13 (Wednesday), Atlantis will – weather permitting – return to her home at the Kennedy Space Center with a mid-morning landing at the Shuttle Landing Facility.

However, Atlantis’ crew may have to place Atlantis into a slightly different orientation during certain portions of the post-undock timeline to accommodate the need to maintain thruster L3D’s temperature since that thruster’s heater has failed “off.”

According to the Mission Evaluation Room (MER), the L3D thruster heater failure is classified as MER-02 – or the second MER problem recorded during Atlantis’ STS-132/ULF-4 flight.

Both the L2D and L4D thrusters – the adjacent thrusters – performed nominally with standard heater activation when their injector temperatures reached ~75 deg F.

For the L3D thruster, a temperature of ~60 deg F was maintained until FD-2 when, during the NC-3 course adjustment burn, the L3D thruster fired twice – thus raising the thruster temperature to 72 deg F.

“From the observed rate of temperature decline (approx. 1 deg/hr) the jet temperatures were not predicted to drop low enough to produce thruster leakage or trigger a Fail Leak RM alert overnight; therefore, no vehicle attitude or jet priority changes were performed prior to Crew Sleep,” notes the MER document.

During the on orbit overnight hours, the L3D thruster temperature dropped to 62 deg F and thermal analysis indicated that the thruster temperature would not drop to “leakage” temperatures. This, coupled with the standard thruster jet firings for rendezvous and docking, brought the thruster temperature to over 100 deg F.

The thruster temperature is important because, while the thruster valve design is certified for operations as low as 40 deg F, the thruster valves are known to leak at temperatures below 50 deg F.

“For a failed off heater, thermal analysis has shown that the valve temperature is ~ 5 deg F warmer than the injector temperature instrumentation,” notes the MER-02 problem report. Because of this finding, an OMRSD requirement was instated (back in the 1980s) to ensure that the thruster valve temperatures are maintained above 50 deg F during ground processing – a rule carried over into on orbit operations.

For the thruster on Atlantis, the document notes that the next worst case failure would be a ‘Fail Leak.’ “Sufficient redundancy exists – two other thrusters on the same side and direction (L2D & L4D) – such that no special procedures are required.”

Nonetheless, should a leak occur, the propellant loss or contamination could be staved by closing the L3 manifold isolation valves.

“Per flight rule C2-2C, the manifold would be closed immediately regardless of the injector temperatures if the jet is suspected to be leaking due to contamination concerns.”

Closure of the manifold would result in the loss of the L3L and L3A thrusters as well as the L3D thruster; however, two redundant thrusters would still be available in each of the affected directions.

Failure of the L3D thruster during the docked portion of the mission was negated due to the mated beta angle which prevented the L3D thruster temperature from dropping below approximately 50 deg F.

However, a greater degree of uncertainty exists in the post-undocking timeframe. “Drain panel heater cycling, which warms L3D injectors about 4F per cycle, is expected in the post undocking -ZLV -XVV attitudes, but the exact duty cycle is hard to predict due to several attitude changes,” notes the MER document.

Due to these uncertainties, temperatures as low as 40 deg F could be had in the post-undocking timeframe.

However, “Thruster temperature can be maintained with the nominal thermal environment, thruster firings, and attitude changes.”

Additionally, non-nominal thruster firings and attitude changes could be employed to maintain thruster temperatures. But, should these thruster firings and attitude controls fail to maintain thruster temperature, the thruster could be declared failed.

If this were to happen, there would be no serious impact to the remainder of Atlantis’ mission and a Nominal End of Mission (NEOM) would be carried out thanks to the redundancy provided by other thrusters.

Therefore, since a loss of the L3D thruster would still result in a NEOM, the MER problem report indicates that any off-nominal thruster firing or orbiter attitude change to maintain thruster temperature would likely be declared unnecessary by the Flight Control team.

This thought of declaring specific action to maintain thruster temperature as unnecessary was confirmed by the MOD (Mission Operations Directorate) and PROP (Propellant) console in Mission Control in a FD-8 presentation by OMS/RCS – also available for download on L2.

“Recommendations: Place thruster in last priority after [ISS] flyaround and take no further actions since predictions are that L3D will remain above 47 deg F.”

However, “Due to analysis uncertainty, it is prudent to determine alternate attitude(s) that could be used if updated analysis predicts lower temps or if actual behavior varies from predicted”

However, a change to the nominal post-undock attitudes would mean an increase in potential MMOD (Micro-Meteoroid Orbiting Debris) risk.

According to the FD-8 OMS/RCS report, “Vehicle attitude changes to place L3D in warmer Environment [would result in] increased MMOD risk.”

The increased risk would translate to approximately 5%, from 1:379 to 1:361 – still well within the acceptable risk matrix for the SSP (Space Shuttle Program).

Furthermore, full data readings on the health of the L3D and other shutdown thrusters would be maintained through EOM (End of Mission) since the thruster’s instrumentation is not affected by the heater failure.

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]]>http://www.nasaspaceflight.com/2010/05/atlantis-undocks-from-iss-potential-thruster-heater-failure-workaround/feed/0STS-132: Atlantis and the ISS set to bid farewell for likely the final timehttp://www.nasaspaceflight.com/2010/05/sts-132-atlantis-iss-set-to-bid-farewell-for-likely-the-final-time/
http://www.nasaspaceflight.com/2010/05/sts-132-atlantis-iss-set-to-bid-farewell-for-likely-the-final-time/#commentsSun, 23 May 2010 02:32:27 +0000http://www.nasaspaceflight.com/?p=14768
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]]>There’s always a chance the unavoidable end of the shuttle program may be at least paced out via at least one additional flight, although the official schedule continues to dictate that Flight Day 10 of STS-132 will be the last time Atlantis will be docked with the International Space Station (ISS).

Atlantis Status:

Her final hours with the orbital outpost have earned praise from engineers, managers and astronauts alike, most of whom have moved away from the politically correct “it” to the traditionally correct “her” when speaking directly of the famous spacecraft.

While the current NASA administrator is himself a veteran shuttle Commander, his comment that people will have forgotten how humans used to travel into space in 10 years time appears to have no basis in reality, if the tributes for the orbiter’s swansong mission – which continue to flood in from public and officials alike – are anything to go by.

General Bolden, at least, remains less than enthusiastic about any plan that does not end the Shuttle Program as soon as possible, as he continues to champion the deeply unpopular proposal outlined in President Obama’s FY2011 budget.

“As far as the current mission goes, there was a little bit of bad luck,” noted SSP (Space Shuttle Program) manager John Shannon on the Shuttle Standup/Integration report (L2) – in reviewing the first part of the mission. “It was just very strange how that cable got routed right between the connector and the little stanchion piece that kept it from tilting up on our inspection.”

While the unit is now able to translate through the required movements that will allow for the Laser Dynamic Range Imager (LDRI) to finally complete a full scan of Atlantis’ RCC panels, Mr Shannon praised the teams for utilizing a variety of assets to allow for the clearance of the vehicle’s Thermal Protection System (TPS) for entry.

“The team has done an amazing job of looking at options and alternative ways of getting inspection data. The RPM looked like it went really well. Overall, it looks like a really clean vehicle. There (were) really (no) reasons to suspect any damage to the vehicle. We will go do the risk trades to get as much inspection data as possible before undocking.”

Although the discussions took several days to conclude, the process of clearing Atlantis from any TPS concerns was typically methodical, and carried out at a pace that ensured the Damage Assessment Team (DAT) presented their recommendations only when they were ready to do so.

All but one of the Atlantis’ array of thrusters will be available for undocking, following an issue with the L3D RCS (Reaction Control System) thruster’s heater shortly after entering orbit. However, concerns the thruster may start to leak – itself not a major impact – have been allayed by good temperature management whilst on orbit.

“No heater cycles have been observed on this thruster. The lowest injector temperatures observed during this shift were 71.7 deg F for fuel and 72.7 deg F for oxidizer.” A full overview of the L3D management plan for post docking will be published in the next article.

“25 of 38 primary thrusters have been fired. No new Primary thrusters were fired since previous report,” with all 38 thrusters set for a two pulse test on EOM-1 (End Of Mission minus one day) during pre-entry checkouts of Atlantis’ systems.

Atlantis’ three Auxiliary Power Units (APUs) and Fuel Cells all continue to show good health, bar a small issue with Fuel Cell 3 noted via its monitoring hardware – although the FC continues to operate nominally.

“Fuel Cell 3, s/n 118, O2 flow meter indication continues to be erratic. It did indicate an increase in flow at the beginning of the fuel cell purge and a decrease at the end of the purge, verifying proper purge valve operation.”

According to the flight plan, the undocking late in the crew day will not allow for a water dump – as per usual – pending any change of plan by the Mission Management Team (MMT). However, Atlantis has enough spare capacity to allow the dump to occur on Flight Day 11 if required.

“Life Support Subsystem is operating nominal, working no issues. Total GN2 = 294.1 lbs. Total Supply water = 391.4 lbs (large transfer to ISS). Total waste water = 58.6 percent (100 lbs),” noted the MER’s most recent status report.

Nominal performance is mirrored throughout the system report, which has become the norm on most recent flights, though under appreciated given the complexity of the vehicle.

“A review of the GPS Data during this period confirmed that the GPS was operating nominally. The GPS team is not working on any issues or funnies,” added examples of the MER status overview. “The Flight Control System is operating nominally. All communications subsystems are performing well. The DPS (Data Processing System) HW (Hardware) team is not working any issues at this time.”

Atlantis is due to undock from the ISS at 10:22am Central Time, prior to a one lap flyaround of the Station, and the main separation burn at 12:05pm Central.